Exhaust stack



FIG. 1 is a perspective view of a first variant of the exhaust stack;

FIG. 2 is one side view thereof;

FIG. 3 is the other side view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a front view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a perspective view of a second variant of the exhaust stack;

FIG. 9 is a front view thereof;

FIG. 10 is a back view thereof;

FIG. 11 is one side view thereof;

FIG. 12 is the other side view thereof;

FIG. 13 is a top view thereof;

FIG. 14 is a bottom view thereof;

FIG. 15 is a perspective view of a third variant of the exhaust stack;

FIG. 16 is a front view thereof;

FIG. 17 is a back view thereof;

FIG. 18 is one side view thereof;

FIG. 19 is the other side view thereof;

FIG. 20 is a top view thereof; and,

FIG. 21 is a bottom view thereof. 

The ornamental design for an exhaust stack, as shown and described. 